The objectives of the Dartmouth University U19 CMCR program are to develop field biodosimetry techniques that are based on ex vivo and in vivo electron paramagnetic resonance (EPR) spectrometry measurements of a radiation-induced signal (RIS) in finger/toe nails (nails) or teeth. In this project (2), the ex vivo EPR method for measuring nails is further developed towards a field deployable application. To achieve this goal, four objectives have been defined that address signal characterization, sample treatment and signal deconvolution to remove interfering signals, validation of test methods, identification and characterization of factors that have the potential to impact the variability of the RIS signal, and establish methods for data acquisition, processing and output suitable for use by non-expert operators and ER managers under field conditions. Characterization of the overall signal, the spectral components and pursuing a systematic investigation of the molecular basis of the EPR signals in both unirradiated and irradiated nails is important towards developing approaches for separating the radiation-induced signal from a mechanically-induced signal (MIS). Some aspects of these studies will utilize the data from Project 3, which will provide EPR spectra of nails without clipping, and therefore help to differentiate more clearly the origin and nature of the signals from the clipping process. The result of this set of studies is the development of a basis set of spectral components of the RIS an MIS signals, coupled with the decay kinetics of the separate component signals that are integrated into a spectrum deconvolution procedure for extracting the RIS component signal. Variability in RIS and MIS signals are to be characterized with respect to nail water content, demographics (i.e. age, race), systemic variables (pregnancy, diet/supplements, nail disorders) and fungal infection. Finally, delineating a field-usable method for sample procurement, placement of the samples into the spectrometer, the analytic software to determine the dose, and delineation of factors that if present need to be considered in the calibration of the results. While the construction of a field-deployable prototype that meets the overall goals of the Center will be carried out in collaboration with the instrumental core at Dartmouth, this project will develop the methodology to be implemented in the development and construction.